AgPest Alert: 5 March 2020

Be vigilant for Velvetleaf

Region: All NZ

In 2016 velvetleaf seed was introduced to NZ as a contaminant of fodder beet seed and planted in many properties throughout NZ. To date, more than 250 properties have been found to be infested with this terrible weed. Six different lines of fodder beet seed have been identified as contaminated but there could be others that were not picked up. Similarly, there may be paddocks where velvetleaf was present but not found. Therefore, if you have either grown fodder beet or received fodder beet onto your property you need to be vigilant and keep an eye out for this weed and do not let it establish on your property. Last year was a cool year and no velvetleaf was found in the South Island but it was found at some North Island sites. This year is much warmer and more velvetleaf is expected to germinate.

Velvetleaf is declared Unwanted Organism by MPI and occurrences must be reported and dealt with. For more information phone the MPI hotline 0800 80 99 66, visit MPI or AgPest online or contact your regional council.

Direct drilling new pasture? Look for slugs and grass grub.

Region: All NZ

If pasture establishment by direct drilling is going to be used, check those pastures for slugs and grass grub as even low numbers can devastate young seedlings of pasture or crop plants. Wet sacks can be laid in the paddock, slugs will shelter under these and be seen on the pasture surface if inspected after 2-3 days – more than 2 slugs per sack could result in seedling loss. To detect grass grub dig at least 10 15 x15 cm holes 15 cm deep and search the soil – as few as 1 grub/hole could cause damage.

Control Californian thistle by mowing in the rain

Region: All NZ

Mowing Californian thistle during rainfall can improve control of this weed by 30% as compared to mowing during dry weather. Best time to do this “wet mowing” is in February/March when the fungi thought to be responsible for this effect are producing spores on the thistle. The effect is likely to be greatest if some members of the thistle population to be mowed are showing signs of disease (wilting, yellowing, dieback).

Ordering grass seed? Select endophyte

Region: All NZ

When ordering grass seed select suitable endophytes and check that the endophyte you select has been assessed in the grass variety you order. In ryegrass AR1,AR37 and diploids with NEA2 will protect against Argentine stem weevil, AR37, Endo5 and NEA2 against black beetle and AR37 against porina. See DairyNZ Pasture Renewal Guide for a guide to endophyte selection or the cultivar selector on Dairy NZ’s Forage Value Index.

Endophyte levels in the seed should be at least 70% and have been assessed in the last 3 months.

Late flights of porina

Region: Hawke’s Bay, Taranaki, Manawatū, Whanganui, Wellington

Late flights of porina may occur in the North Island. These could result in damage appearing in June in infested paddocks. Look to apply diflubenzuron in late April-mid May.

Inspect 2- and 3-year-old pastures for grass grub

Region: Bay of Plenty, Waikato, Gisborne, Hawke’s Bay, Taranaki, Manawatū, Whanganui, Wellington, Nelson, Tasman, Marlborough, Canterbury, West Coast, Otago, Southland.

In grass grub prone areas 2- and 3-year-old pastures should be inspected to determine if potentially damaging levels are present.
Early treatment will offer the most protection and maximise returns from the cost of intervention.




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